The patentee has for years manufactured, sold and used a well point sampler or ground probe for sampling and analyzing shallow groundwater down to a maximum of approximately ten (10) feet. The well point sampler is used for extracting groundwater samples around lake shores or whatever shallow groundwater exists, and it essentially replaces tedious hand-augering to obtain representative samples of groundwater for water quality analysis.
The well point sampler includes a point threaded to a tubular slotted sleeve (screen), and the latter are connected to lengths of tubing which are driven into the ground to a desired depth. A tube is connected to the screen and to a pump at ground level, and samples of groundwater can thereby be obtained and analyzed. The well point sampler can also be used in this manner in conjunction with a conductivity meter for profiling subsurface plumes.
In recent years the sampling of soil vapors (gasoline, oil and like hydrocarbons) has become extremely important from the standpoint of preventing water quality degradation, inadvertent explosions, etc. The well point sampler is likewise capable of providing vertical profiling of gasoline or oil vapors in the soil by simply connecting the tube to a meter for detecting combustible gases. This can be done at gasoline service stations, for example, to quickly identify the existence of leaking tanks and do so without interruption of service during such testing. Furthermore, as the well point sampler is driven into the ground, readings can be progressively taken and as the probe point descends, high readings caused by surface oil spills would progressively decrease, but at deeper depths the rapid rise of combustible vapors would indicate a region of saturated soil and provide a positive test of leakage from an associated tank.
The fact that soil and groundwater contamination from spills and leaks of petroleum hydrocarbons presents a serious environmental problem is evidence by a recent publication of the American Petroleum Institute of 1220 L Street, N.W., Washington, D.C. 20005 entitled Detection of Hydrocarbons in Groundwater by Analysis of Shallow Soil Gas/Vapor which is published by the Environmental Affairs Department, and is identified by API PUBLICATION NO. 4394 of May, 1985. This document represents a consolidation/compilation of a search of open literature relating to subsurface sampling and analyzing techniques, including utilization of ground probes. While driveable ground probes were found to be highly efficient, they tended to be susceptible to "plugging" during insertion, and samples were difficult to obtain in wet, clayey soils. In at least one case a mesh screen was used to prevent blockage of the sample entry holes of the driveable ground probe (See page 44 of the latter publication). Thus, while this publication recognizes driveable ground probes as the preferred types to use for a groundwater contamination investigation, disadvantages noted include the fact that the sample entry ports can become blocked by solid particles and poor results have been obtained for wet, clayey soils (See page 56 of the latter publication).